Asian cultivated rice is one of the most important cereal crops globally,feeding approximately 50%of the world's population.Increasing rice nitrogen use efficiency(NUE)is crucial for achieving high yields with low...Asian cultivated rice is one of the most important cereal crops globally,feeding approximately 50%of the world's population.Increasing rice nitrogen use efficiency(NUE)is crucial for achieving high yields with low nitrogen inputs(Xu et al.,2012;Hu et al.,2023).However,modern cultivars are typically bred for high yields through excessive nitrogen fertilizer use,leading to the loss of beneficial alleles associated with high NUE during the breeding process(Wang and Peng,2017;Hu et al.,2023).Genetic improvement for high NUE should be a key strategy in breeding“Green Super Rice”(GSR)(Yu et al.,2021)and water-saving and drought-resistance rice(WDR)(Luo,2010;Xia et al.,2022)for sustainable agriculture.Asian cultivated rice is highly diverse and harbors vital genetic variants essential for adaptation to different environments(Wing et al.,2018).展开更多
Soybean(Glycine max)is a globally important crop that serves as a primary source of edible oil and protein for both humans and animals.Cultivated soybean varieties exhibit considerable genetic diversity depending on t...Soybean(Glycine max)is a globally important crop that serves as a primary source of edible oil and protein for both humans and animals.Cultivated soybean varieties exhibit considerable genetic diversity depending on their geographical origin.Heinong 531(HN531)is an elite cultivar that was released in China in June 2021 with 22.34%seed oil,high resistance to soybean cyst nematode(SCN)race 3,and enhanced yield.However,the genetic basis for these desirable agronomic traits is unclear.In this study,we generated a high-quality genome assembly for HN531 and used it to systematically analyze genes related to agronomic traits such as resistance to SCN.The assembled genome spans 981.20 Mb,featuring a contig N50 of 19.47 Mb,and contains 58,151 predicted gene models.Pan-genomic comparison with 27 previously reported soybean genomes revealed 95,071 structural variants(SVs)of>50 bp,of which 602 were HN531-specific.Furthermore,we identified a copy number variation at rhg1 that underlies resistance to SCN,and we found elite alleles of functional genes underlying important agronomic traits such as seed oil content,adaptability,and yield.This high-quality HN531 genome can be used to explore the genetic basis for the excellent agronomic traits of this cultivar,and is a valuable resource for breeders aiming to improve HN531 and related cultivars.展开更多
Irrigation methods and nitrogen(N) fertilization modes have complicated impacts on wheat physiology, growth, and development, leading to the regulation of wheat grain yield and quality. However, the optimal water-N co...Irrigation methods and nitrogen(N) fertilization modes have complicated impacts on wheat physiology, growth, and development, leading to the regulation of wheat grain yield and quality. However, the optimal water-N combination for drip-irrigated winter wheat remains unclear. A two-year field study was conducted to evaluate the influences of various N-fertigation and water regimes on wheat post-anthesis grain weight variation, yield, grain NPK content, and grain quality. The two irrigation quotas were I_(45)(irrigation when crop evapotranspiration reduced by effective rainfall(ETa-P) reaches 45 mm) and I_(30)(irrigation when ETa-P reaches 30 mm), while the six N application rates were N_(0–100)(100% at jointing/booting), N_(25–75)(25% at sowing and 75% at jointing/booting), N_(50–50)(50% at sowing and 50% at jointing/booting), N_(75–25)(75% at sowing and 25% at jointing/booting), N_(100–0)(100% at sowing), and SRF100(100% of slow-release fertilizer at sowing). The experimental findings showed that post-anthesis grain weight variation, grain yield, grain NPK content, and grain quality were all markedly influenced by the various irrigation schedules and N-fertilization modes. The N_(50–50)treatment was more beneficial for winter wheat post-anthesis grain weight variation than the N_(100–0)and N_(0–100)treatments under the two irrigation quotas and during the two seasons. The highest grain yields of 9.72 and9.94(t ha^(-1)) were obtained with the I_(45)N_(50–50)treatment in 2020–2021 and 2021–2022, respectively. The grain crudeprotein was higher in the I_(45)SRF100treatment during the two seasons. The I_(45)N_(100–0)combination significantly(P<0.05)enhanced the content of grain total starch by 7.30 and 8.23% compared with the I_(45)N_(0–100)and I_(30)N_(0–100)treatments,respectively, during the 2021–2021 season. The I_(45)N_(100–0)treatment significantly(P<0.05) enhanced the content ofgrain total starch concentration by 7.77, 7.62 and 7.88% compared with the I_(45)N_(0–100), I_(30)N_(0–100), and I_(30)N_(25–75)treatments,respectively, in the 2021–2022 season. The principal component analysis(PCA) indicated that the N_(50–50)splitN-fertigation mode could be the optimal choice for farmers during winter wheat production via drip irrigation.展开更多
Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and ...Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.展开更多
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive degeneration of upper and lower motor neurons in the brainstem and spinal cord,leading to muscle weakness,para...Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive degeneration of upper and lower motor neurons in the brainstem and spinal cord,leading to muscle weakness,paralysis,and respiratory failure (Morgan and Orrell,2016).展开更多
The aim of this study was to investigate the responses of frost dates to global warming and its influences on grain yields. In this study, based on the frost date series defined by daily minimum ground temperature, th...The aim of this study was to investigate the responses of frost dates to global warming and its influences on grain yields. In this study, based on the frost date series defined by daily minimum ground temperature, the spatial and temporal characteristics of first frost date （FFD）, last frost date （LFD） and frost-free period （FFP） were analyzed. The impact of extending FFP on major crop yields was also studied. The results were as follows： FFD showed a significantly delaying trend of 2.2 d/10 y, and LFD presented an advancing trend of 2.4 d/10 y. FFP extended at a rate of 4.5 d/10 y due to the later FFD and earlier LFD. The most obvious trend of FFD was in westem Henan, while the most significant trend of LFD and FFP oc- curred in south central parts of the study area. However, in eestem region, the trends of FFD, LFD and FFP were not so obvious. Major crop yield showed a sig- nificant correlation with frost-free period for Henan during 1961-2013. The yields of grain, rice, wheat, and maize increased by 79.5, 90.0, 79.5 and 70.5 kg/hm2 with FFP extending by one day.展开更多
The variation and influence factors of yield gravity center of flue-cured tobacco in Hunan were studied in 2006-2015 by regional gravity center method and grey correlation analysis. The results showed that the yields ...The variation and influence factors of yield gravity center of flue-cured tobacco in Hunan were studied in 2006-2015 by regional gravity center method and grey correlation analysis. The results showed that the yields of flue-cured tobacco in various areas in Hunan were mainly of the growing with fluctuation type. The yield gravity centers in the whole province and eastern, southern and western Hunan tobacco-growing areas overall moved in the north by west, south by west, west by south, and south by east directions, respectively; and the movements in the south-north direction were in order of eastern Hunan tobacco-growing area 〉whole province 〉western Hunan tobacco-growing area 〉southern Hunan tobacco-growing area, and the movements inthe east-west direction showed an order of eastern Hunan tobecco-growing area〉western Hunan tobacco-growing area〉whole province〉 southern Hunan tobacco-growing area. The main influence factors of the coordinates of the longitudes and the latitudes differed. The main influence factor was planting area in most cities or counties in the whole province, and was per unit area yield in a few cities or counties. It is advised to construct the ＂one main body and two wings＂ development pattern of flue-cured tobacco production in Hunan with southern Hunan tobacco-growing area as the main body and western and eastern Hunan tobacco-growing areas as the two wings.展开更多
Despite the improvement in cultivar characters and management practices, large gaps between the attainable and potential yields still exist in winter wheat of China. Quantifying the crop potential yield is essential f...Despite the improvement in cultivar characters and management practices, large gaps between the attainable and potential yields still exist in winter wheat of China. Quantifying the crop potential yield is essential for estimating the food production capacity and improving agricultural policies to ensure food security. Gradually descending models and geographic infor- mation system （GIS） technology were employed to characterize the spatial variability of potential yields and yield gaps in winter wheat across the main production region of China. The results showed that during 2000-2010, the average potential yield limited by thermal resource （YGT） was 23.2 Mg ha-1, with larger value in the northern area relative to the southern area. The potential yield limited by the water supply （YGw） generally decreased from north to south, with an average value of 1.9 Mg ha-1 across the entire study region. The highest YGw in the north sub-region （NS） implied that the irrigation and drainage conditions in this sub-region must be improved. The averaged yield loss of winter wheat from nutrient deficiency （YGH） varied between 2.1 and 3.1 Mg ha-1 in the study area, which was greater than the yield loss caused by water limitation. The potential decrease in yield from photo-thermal-water-nutrient-limited production to actual yield （YGo） was over 6.0 Mg ha-1, ranging from 4.9 to 8.3 Mg ha^-1 across the entire study region, and it was more obvious in the southern area than in the northern area. These findings suggest that across the main winter wheat production region, the highest yield gap was induced by thermal resources, followed by other factors, such as the level of farming technology, social policy and economic feasibility. Furthermore, there are opportunities to narrow the yield gaps by making full use of climatic resources and developing a reasonable production plan for winter wheat crops. Thus, meeting the challenges of food security and sustainability in the coming decades is possible but will require considerable changes in water and nutrient management and socio-economic policies.展开更多
Leaf thickness is an important morphological trait in rice. Its association to the yield potential, as of now has not been documented because of the shortage of the equipment which could conveniently measure the leaf ...Leaf thickness is an important morphological trait in rice. Its association to the yield potential, as of now has not been documented because of the shortage of the equipment which could conveniently measure the leaf thickness in rice. In this study, the thickness of top three leaves of 208 cultivars had been determined by a nondestructive rice leaf thickness instrument for the research of the natural variation of leaves thickness and its association to yield traits in indica rice. The results showed that the flag leaf was the thickest, and the 2nd leaf was thicker than the 3rd leaf. Analysis of variance indicated the existence of wide genetic diversity of leaf thickness among the investigated indica rice genotypes. The tight correlation among the thicknesses of the top three leaves means that the leaf thickness traits share one genetic control system. Leaf thickness had a significant positive correlation with leaf length and a positive correlation with leaf width, indicated that thicker leaf was beneficial to increasing the single leaf area. The results of correlation analysis revealed that thicker leaf should be profitable to the leaf erection, higher numbers of grains per panicle and higher grains weight per panicle. However, the significantly negative correlation between leaf thickness and number of panicles per plant counteracted the profitability from increased grains weight per panicle, so that the correlations of the thicknesses of the top three leaves to yield and biomass were positive but not significantly. It has made great progress in the genetic improvement of leaves thickness in inbred indica rice breeding in Guangdong Province, China, since the 1990s.展开更多
Rice has a large number of nitrate or peptide transporter family(NPF) genes, but the effects of most members on rice growth and development are unknown. We report that Os NPF5.16, a nitrate transporter gene with natur...Rice has a large number of nitrate or peptide transporter family(NPF) genes, but the effects of most members on rice growth and development are unknown. We report that Os NPF5.16, a nitrate transporter gene with natural variation in its promoter sequence, is essential for rice growth and yield. The promoter sequence showed various differences between indica and japonica cultivars, and higher expression of Os NPF5.16 was found in indica cultivars with higher plant weight and more tillers than japonica cultivars.Os NPF5.16 was highly expressed in roots, tiller basal parts, and leaf sheaths, and its protein was localized on the plasma membrane. In c RNA-injected Xenopus laevis oocytes, Os NPF5.16 transport of nitrate at high nitrate concentration depended on p H. Overexpression of Os NPF5.16 increased nitrate content and total nitrogen content in leaf sheath as well as biomass and tiller bud length in rice. Elevated expression of Os NPF5.16 increased rice tiller number and grain yield by regulating cytokinin levels. Inhibition of Os NPF5.16 expression showed the opposite effects. Regulating Os NPF5.16 expression has potential for improving rice grain yield.展开更多
Detailed information on venom yield is helpful in preparing antivenoms and treating snakebites, but such information is lacking for many species of venomous snakes. The Chinese cobra(Naja atra) is a large sized, venom...Detailed information on venom yield is helpful in preparing antivenoms and treating snakebites, but such information is lacking for many species of venomous snakes. The Chinese cobra(Naja atra) is a large sized, venomous snake commonly found in southeastern China, where it causes a heavy burden of snakebites. To examine the effects of various factors(morphology, sex, age, season, and geographical origin) on the venom yield in this snake, we collected venom samples of 446 individuals(426 adults and 20 neonates) from 10 populations of N. atra over an eightyear period. We used two variables, lyophilized venom mass(venom yield) and solid content of venom(% solids), to quantify the venom yield. We used linear regression analysis to check if venom yield was related to morphological factors, one-way ANOVA and one-way ANCOVA to detect the sexual, ontogenetic, and geographic variation in venom yield, and repeated-measures ANOVA to examine seasonal shifts in venom yield. Our results indicate that venom yield of N. atra is positively related to the morphological traits examined, with male snakes expelling more venom than females. Venom yield in N. atra was age-related, with elder snakes always expelling more venom than younger ones. Geographic variation in venom yield was also observed, while seasonal variation was not. The solid content of venom was lower in males than in females, but this was not related to morphology, season, age, or geography. Our findings suggest that venom yield in N. atra is influenced by multiple factors, as well as by the interactions among these factors.展开更多
Previous studies demonstrated climate change had reduced rice yield in China, but the magnitude of the reduction and the spatial variations of the impact have remained in controversy to date. Based on a gridded daily ...Previous studies demonstrated climate change had reduced rice yield in China, but the magnitude of the reduction and the spatial variations of the impact have remained in controversy to date. Based on a gridded daily weather dataset, we found there were obvious changes in temperatures, diurnal temperature range, and radiation during the rice-growing season from 1961 to 2010 in China. These changes resulted in a signiifcant decline of simulated national rice yield （simulated with CERES-Rice）, with a magnitude of 11.5%. However, changes in growing-season radiation and diurnal temperature range, not growing-season temperatures, contributed most to the simulated yield reduction, which conifrmed previous estimates by empirical studies. Yield responses to changes of the climatic variables varied across different rice production areas. In rice production areas with the mean growing-season temperature at 12-14＆#176;C and above 20＆#176;C, a 1＆#176;C growing-season warming decreased rice yield by roughly 4%. This decrease was partly attributed to increased heat stresses and shorter growth period under the warmer climate. In some rice areas of the southern China and the Yangtze River Basin where the rice growing-season temperature was greater than 20＆#176;C, decrease in the growing-season radiation partly interpreted the widespread yield decline of the simulation, suggesting the signiifcant negative contribution of recent global dimming on rice production in China＇s main rice areas. Whereas in the northern rice production areas with relatively low growing-season temperature, decrease of the diurnal temperature range was identiifed as the main climatic contributor for the decline of simulated rice yield, with larger decreasing magnitude under cooler areas.展开更多
Biomass yields and concentrations of crude protein（CP）, ether extract（EE）, neutral detergent fiber（NDF）, acid detergent fiber（ADF）, and crude fiber（CF） were analyzed for five cultivars of summer-sown maize（...Biomass yields and concentrations of crude protein（CP）, ether extract（EE）, neutral detergent fiber（NDF）, acid detergent fiber（ADF）, and crude fiber（CF） were analyzed for five cultivars of summer-sown maize（Zea mays L.） stover grown in field trials at three rates of N fertilization, and sampled immediately after grain harvest.The results revealed differences in yields and concentrations of nutrients according to stalk height and hence harvest portion among the cultivars.N application greatly increased biomass yield and CP, especially in upper stalks and to a lesser extent, EE.Concentrations of NDF and ADF decreased as N rate increased.The results show that stovers from all local popular maize cultivars are suitable as animal fodder and that moderate N application improves feed quality of stover.展开更多
Many attentions have been previously focused to identify the multiple biochemical components related to tea quality and health benefits,however, the natural variation of biochemical components present in tea germplasm...Many attentions have been previously focused to identify the multiple biochemical components related to tea quality and health benefits,however, the natural variation of biochemical components present in tea germplasm has not been adequately evaluated. In this study, the main biochemical components, leaf morphological and yield characteristics were evaluated for four rounds of tea leaves in a panel of 87 elite tea cultivars suitable for black, green, or oolong tea. Significant variations were observed among the tea cultivars, as well as seasonal differences in the levels of the free amino acid(FAA), caffeine(CAF), tea polyphenols(TP), water extract(WE) and TP to FAA ratio(TP/FAA). Results showed that the average levels of FAA showed a seasonal change, with the highest level of 4.0% in the 1st spring tea in the cultivars suitable for green tea and the lowest of 3.2% in summer tea in the cultivars suitable for black tea. The average CAF content was highest 3.2% in the cultivars suitable for oolong tea in the 1st spring and the lowest 2.5% in the cultivars suitable for green tea in summer. Limited seasonal and varietal variations were noticed in the average levels of WE among the three categories of tea. In addition, significant natural variation of the morphological characteristics, bud length varying from 2.5 cm to 8.7 cm, bud density from 190.3 buds · m-2to 1 730.3 buds · m-2, mature leaves biomass from 128.4 kg · hm-2to 2 888.4 kg · hm-2, and yield component traits of 100 buds(one bud with two leaves) dry weight from 3.7 g to37.7 g, tea yield/round from 444.6 kg · hm-2to 905.3 kg · hm-2, were observed. The aim of our evaluation was not only to identify the advantages of seasonal and clonal variations but also to provide a new viewpoint for their further application. Representative accessions were selected from the germplasm to promote the establishment of an inherent biochemical constituent expressing the quality of black, green, and oolong tea. The findings might be utilized to establish early selection criteria to enhance the tea breeding and production program.展开更多
Regime of groundwater level is a comprehensive reflection of the hydrogeological environment from the perspective of groundwater. Based on the analysis of the water-level change of 65 groundwater monitoring points fro...Regime of groundwater level is a comprehensive reflection of the hydrogeological environment from the perspective of groundwater. Based on the analysis of the water-level change of 65 groundwater monitoring points from 1987 to 1990, it is found that intermittent cones of depression came into being due to groundwater exploitation in Guilin during the observation period. The buried depth of groundwater in the drawdown cones, the annual variation of water level and specific yield have higher values. Improvement has been made to the formula of infiltration coefficient of precipitation. By using the precipitation response data recorded at every 15 minutes for water level of No. 9 borehole which is near Zengpiyan Cave, the specific yield of phreatic variation zone is indirectly calculated by using the modified formula. The results are range from 0.012 to 0.462 and the spatial distribution of specific yield is ascertained. These make up the deficiency that empirical values cannot be categorized based on the actual conditions. What’s more, the widely used Aviriyanover’s empirical formula is poorly applicable to karst area. This is due to its strict requirement for outside conditions, such as shallow buried depth, homogeneous aquifer medium and small hydraulic gradient.展开更多
Environmental conditions greatly affect the growth of rice. To investigate the geographic differences in yield formation of single-season high-yielding hybrid rice in southern China, experiments were conducted in 2017...Environmental conditions greatly affect the growth of rice. To investigate the geographic differences in yield formation of single-season high-yielding hybrid rice in southern China, experiments were conducted in 2017 and 2018 in the upper and middle–lower reaches of the Yangtze River with 10–30 main locally planted high-yielding hybrid cultivars used as materials. Compared with rice planted in the middle–lower reaches of the Yangtze River, rice planted in the upper reaches has a longer tillering duration, higher accumulated temperature(≥10℃) during tillering period, but lower accumulated temperature and solar radiation from initial booting to maturity. Yield traits comparison between the upper and the middle–lower reaches of Yangtze River showed that the former had 48.1% more panicles per unit area while the latter had 46.4% more grains per panicle;the rice yield in the former was positively correlated with the seed setting rate and the dry matter accumulation before heading, while the latter was positively correlated with grains per panicle and dry matter accumulation from booting to maturity. Comparison of the same variety Tianyouhuazhan planted in different regions showed there was a significant positive correlation between panicle number and the duration of and accumulated temperature during the tillering period(r=0.982^(**), r=0.993^(**), respectively), and between grains per panicle and accumulated solar radiation during booting period(r=0.952~*). In the upper reaches of the Yangtze River, more than 90% of cultivars with an yield of greater than 11 t ha^(–1) had an effective panicle number of 250–340 m^(–2), and there was a significant negative correlation between seed setting rate and grains per panicle;therefore, the high-yielding rice production in these regions with a long effective tillering period(>40 d) should choose varieties with moderate grains per panicle, adopt crop managements such as good fertilizer and water measures during vegetative growth period to ensure a certain number of effective panicles, and to increase the dry matter accumulation before heading. While in regions with a short effective tillering period(<20 d) but good sunshine conditions during the reproductive growth period, such as the middle–lower reaches of the Yangtze River, high-yielding rice production should choose cultivars with large panicles, adopt good water and fertilizer managements during the reproductive growth period to ensure the formation of large panicles and the increase of dry matter accumulation after heading.展开更多
The interactions on rainfed soybean yield among planting date, maturity, and year-to-yearclimate change were studied using CROPGRO-soybean model. Simulations were based on 19 plantingdates, maturity groupsⅢ, ⅣandⅤ,...The interactions on rainfed soybean yield among planting date, maturity, and year-to-yearclimate change were studied using CROPGRO-soybean model. Simulations were based on 19 plantingdates, maturity groupsⅢ, ⅣandⅤ, 30 years recorded weather data from Corbin, Suffolk,West Point in Virginia, USA. Yield was similar on early plantings and went down with lateplantings. Both grand and year-to-year variation of soybean yield declined linearly withplanting date. Year-to-year climate variation was dominant yield variation source inrainfed soybean production. Interaction occurred between planting date and maturity.Optimal planting dates for different sites lied within 130th-170th day of a year.Irrigation is recommended for profitable crops, especially in Corbin and West Point.展开更多
Based on the surveys and the statistic data during 1980-2003, the variation character of grain yield per unit area in Northeast China and its main factors have been discussed by the methods of statistics and grey corr...Based on the surveys and the statistic data during 1980-2003, the variation character of grain yield per unit area in Northeast China and its main factors have been discussed by the methods of statistics and grey correlation analysis. The results show that: 1) the grain yield per unit area has been taking on an increasing trend in the recent 20 years. It increased from 2519.80kg/ha in 1980 to 4216.11kg/ha in 2003, with an increasing rate of 67.32%; 2) the variation of grain yield per unit area is considerably prominent and its range is also very great, with the maximal increase rate of 42.59% and maximal decrease rate of 21.13%, respectively, which are far above the whole Chinese average level; 3) the variation of main crops' yield per unit area is remarkable, which takes on the character that the yield of corn is much higher than that of soybean and rice; and 4) the grey correlation analysis shows that the most important factors impacting the variation of grain yield per unit area are the total power of agricultural machinery, the consumption of chemical fertilizer and effective irrigated area. However, the influence of natural disaster and income level should not be ignored. Effective ways to improve grain yield per unit area are to construct farmland improvement groundwork, reclaim the middle- and low-yield farmland, etc.展开更多
In this work,variation in the dynamic recrystallization(DRX)and dynamic precipitation behavior of AZ80 alloy during extrusion due to changes in extrusion temperature was investigated,and the resultant microstructure a...In this work,variation in the dynamic recrystallization(DRX)and dynamic precipitation behavior of AZ80 alloy during extrusion due to changes in extrusion temperature was investigated,and the resultant microstructure and yield asymmetry were analyzed.As the extrusion temperature increases from 250℃to 350℃,the primary DRX mechanism changes from twin-induced DRX to discontinuous DRX,resulting in an increase in the DRX area fraction and un DRXed grain size.In addition,as the extrusion temperature rises,Mg17Al12 precipitation during extrusion decreases sharply throughout the extruded material.The reduction in the compressive yield strength(CYS)with increasing extrusion temperature is more pronounced than it is for the tensile yield strength(TYS),which ultimately increases the yield asymmetry of the extruded material.The higher extrusion temperature has less of an influence on the TYS due to the promotion of certain hardening effects.On the other hand,the greater reduction in the CYS is attributed to the increased fraction and size of regions in which{1012}twins predominantly form and the lower amount of precipitates,which effectively facilitates{1012}twinning.展开更多
Better understanding of the factors that influence crop nitrogen(N) requirement plays an important role in improving regional N recommendations for rice(Oryza sativa L.) production. We collected data from 1 280 plot-l...Better understanding of the factors that influence crop nitrogen(N) requirement plays an important role in improving regional N recommendations for rice(Oryza sativa L.) production. We collected data from 1 280 plot-level measurements in different reaches of the Yangtze River, China to determine which factors contributed to variability in N requirement in rice. Yield, variety, and cropping system were significantly related to N requirement. The N requirement remained consistent at about 18.6 kg N Mg^(-1)grain as grain yield increased from 7 to 9 Mg ha^(-1), then decreased to 18.1, 16.9, and 15.9 kg N Mg^(-1)grain as yield increased to 9–10, 10–11, and > 11 Mg ha^(-1), respectively. The decreased requirement for N with increasing yield was attributable to declining N concentrations in grain and straw and increased harvest index. Super rice variety had lower N requirement(17.7 kg N Mg^(-1)grain) than ordinary inbred and hybrid varieties(18.5 and 18.3 kg N Mg^(-1)grain, respectively), which was a result of lower grain and straw N concentrations of super rice. The N requirements were 19.2, 17.8, and 17.5 kg N Mg^(-1)grain for early, middle, and late rice cropping systems, respectively. In conclusion, the rice N requirement was affected by multiple factors, including yield, variety, and cropping system, all of which should be considered when planning for optimal N management.展开更多
基金supported by Joint Funds of National Natural Science Foundation of China(U24A20399)Natural Science Foundation of Shanghai(23JC1403500,22ZR1455300)+2 种基金Specific university discipline construction project(2023B10564002,2023B10564004)Shanghai Agricultural Science and Technology Innovation Program(2024-02-08-00-12-F00028)Earmarked Fund for China Agriculture Research System(CARS-01).
文摘Asian cultivated rice is one of the most important cereal crops globally,feeding approximately 50%of the world's population.Increasing rice nitrogen use efficiency(NUE)is crucial for achieving high yields with low nitrogen inputs(Xu et al.,2012;Hu et al.,2023).However,modern cultivars are typically bred for high yields through excessive nitrogen fertilizer use,leading to the loss of beneficial alleles associated with high NUE during the breeding process(Wang and Peng,2017;Hu et al.,2023).Genetic improvement for high NUE should be a key strategy in breeding“Green Super Rice”(GSR)(Yu et al.,2021)and water-saving and drought-resistance rice(WDR)(Luo,2010;Xia et al.,2022)for sustainable agriculture.Asian cultivated rice is highly diverse and harbors vital genetic variants essential for adaptation to different environments(Wing et al.,2018).
基金supported by National Natural Science Foundation of China(32201759,32172002)Inner Mongolia Innovation Center of Biological Breeding Technology,National Key Research and Development Program of China(2021YFD1201600)+1 种基金Earmarked Fund for CARS(CARS-04-PS01)Agricultural Science and Technology Innovation Program(ASTIP).
文摘Soybean(Glycine max)is a globally important crop that serves as a primary source of edible oil and protein for both humans and animals.Cultivated soybean varieties exhibit considerable genetic diversity depending on their geographical origin.Heinong 531(HN531)is an elite cultivar that was released in China in June 2021 with 22.34%seed oil,high resistance to soybean cyst nematode(SCN)race 3,and enhanced yield.However,the genetic basis for these desirable agronomic traits is unclear.In this study,we generated a high-quality genome assembly for HN531 and used it to systematically analyze genes related to agronomic traits such as resistance to SCN.The assembled genome spans 981.20 Mb,featuring a contig N50 of 19.47 Mb,and contains 58,151 predicted gene models.Pan-genomic comparison with 27 previously reported soybean genomes revealed 95,071 structural variants(SVs)of>50 bp,of which 602 were HN531-specific.Furthermore,we identified a copy number variation at rhg1 that underlies resistance to SCN,and we found elite alleles of functional genes underlying important agronomic traits such as seed oil content,adaptability,and yield.This high-quality HN531 genome can be used to explore the genetic basis for the excellent agronomic traits of this cultivar,and is a valuable resource for breeders aiming to improve HN531 and related cultivars.
基金supported by the China Agriculture Research System of MOF and MARA (CARS-03-19)the National Natural Science Foundation of China (51879267)the Agricultural Science and Technology Innovation Program (ASTIP), Chinese Academy of Agricultural Sciences。
文摘Irrigation methods and nitrogen(N) fertilization modes have complicated impacts on wheat physiology, growth, and development, leading to the regulation of wheat grain yield and quality. However, the optimal water-N combination for drip-irrigated winter wheat remains unclear. A two-year field study was conducted to evaluate the influences of various N-fertigation and water regimes on wheat post-anthesis grain weight variation, yield, grain NPK content, and grain quality. The two irrigation quotas were I_(45)(irrigation when crop evapotranspiration reduced by effective rainfall(ETa-P) reaches 45 mm) and I_(30)(irrigation when ETa-P reaches 30 mm), while the six N application rates were N_(0–100)(100% at jointing/booting), N_(25–75)(25% at sowing and 75% at jointing/booting), N_(50–50)(50% at sowing and 50% at jointing/booting), N_(75–25)(75% at sowing and 25% at jointing/booting), N_(100–0)(100% at sowing), and SRF100(100% of slow-release fertilizer at sowing). The experimental findings showed that post-anthesis grain weight variation, grain yield, grain NPK content, and grain quality were all markedly influenced by the various irrigation schedules and N-fertilization modes. The N_(50–50)treatment was more beneficial for winter wheat post-anthesis grain weight variation than the N_(100–0)and N_(0–100)treatments under the two irrigation quotas and during the two seasons. The highest grain yields of 9.72 and9.94(t ha^(-1)) were obtained with the I_(45)N_(50–50)treatment in 2020–2021 and 2021–2022, respectively. The grain crudeprotein was higher in the I_(45)SRF100treatment during the two seasons. The I_(45)N_(100–0)combination significantly(P<0.05)enhanced the content of grain total starch by 7.30 and 8.23% compared with the I_(45)N_(0–100)and I_(30)N_(0–100)treatments,respectively, during the 2021–2021 season. The I_(45)N_(100–0)treatment significantly(P<0.05) enhanced the content ofgrain total starch concentration by 7.77, 7.62 and 7.88% compared with the I_(45)N_(0–100), I_(30)N_(0–100), and I_(30)N_(25–75)treatments,respectively, in the 2021–2022 season. The principal component analysis(PCA) indicated that the N_(50–50)splitN-fertigation mode could be the optimal choice for farmers during winter wheat production via drip irrigation.
基金supported by the National Natural Science Foundation of China(Grant Nos.42027804,41775026,and 41075012)。
文摘Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.
文摘Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the progressive degeneration of upper and lower motor neurons in the brainstem and spinal cord,leading to muscle weakness,paralysis,and respiratory failure (Morgan and Orrell,2016).
基金Funded by"Strategic Priority Research Program"of the Chinese Academy of Sciences(XDA05090101,XDA05090104)China Global Change Research Program(2010CB950101,2012CB955403)+2 种基金Basic Research Project of the Ministry of Science and Technology(2011FY120300)Doctor Foundation of Xinyang Normal University(0201403)National Natural Science Foundation of China(41271124,41101549)~~
文摘The aim of this study was to investigate the responses of frost dates to global warming and its influences on grain yields. In this study, based on the frost date series defined by daily minimum ground temperature, the spatial and temporal characteristics of first frost date （FFD）, last frost date （LFD） and frost-free period （FFP） were analyzed. The impact of extending FFP on major crop yields was also studied. The results were as follows： FFD showed a significantly delaying trend of 2.2 d/10 y, and LFD presented an advancing trend of 2.4 d/10 y. FFP extended at a rate of 4.5 d/10 y due to the later FFD and earlier LFD. The most obvious trend of FFD was in westem Henan, while the most significant trend of LFD and FFP oc- curred in south central parts of the study area. However, in eestem region, the trends of FFD, LFD and FFP were not so obvious. Major crop yield showed a sig- nificant correlation with frost-free period for Henan during 1961-2013. The yields of grain, rice, wheat, and maize increased by 79.5, 90.0, 79.5 and 70.5 kg/hm2 with FFP extending by one day.
文摘The variation and influence factors of yield gravity center of flue-cured tobacco in Hunan were studied in 2006-2015 by regional gravity center method and grey correlation analysis. The results showed that the yields of flue-cured tobacco in various areas in Hunan were mainly of the growing with fluctuation type. The yield gravity centers in the whole province and eastern, southern and western Hunan tobacco-growing areas overall moved in the north by west, south by west, west by south, and south by east directions, respectively; and the movements in the south-north direction were in order of eastern Hunan tobacco-growing area 〉whole province 〉western Hunan tobacco-growing area 〉southern Hunan tobacco-growing area, and the movements inthe east-west direction showed an order of eastern Hunan tobecco-growing area〉western Hunan tobacco-growing area〉whole province〉 southern Hunan tobacco-growing area. The main influence factors of the coordinates of the longitudes and the latitudes differed. The main influence factor was planting area in most cities or counties in the whole province, and was per unit area yield in a few cities or counties. It is advised to construct the ＂one main body and two wings＂ development pattern of flue-cured tobacco production in Hunan with southern Hunan tobacco-growing area as the main body and western and eastern Hunan tobacco-growing areas as the two wings.
基金supported by the National High-Tech R&D Program of China(863 Program,2013AA100404)the National Natural Science Foundation of China(31301234 and 31271616)+1 种基金the National Research Foundation for the Doctoral Program of Higher Education of China(20120097110042)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)
文摘Despite the improvement in cultivar characters and management practices, large gaps between the attainable and potential yields still exist in winter wheat of China. Quantifying the crop potential yield is essential for estimating the food production capacity and improving agricultural policies to ensure food security. Gradually descending models and geographic infor- mation system （GIS） technology were employed to characterize the spatial variability of potential yields and yield gaps in winter wheat across the main production region of China. The results showed that during 2000-2010, the average potential yield limited by thermal resource （YGT） was 23.2 Mg ha-1, with larger value in the northern area relative to the southern area. The potential yield limited by the water supply （YGw） generally decreased from north to south, with an average value of 1.9 Mg ha-1 across the entire study region. The highest YGw in the north sub-region （NS） implied that the irrigation and drainage conditions in this sub-region must be improved. The averaged yield loss of winter wheat from nutrient deficiency （YGH） varied between 2.1 and 3.1 Mg ha-1 in the study area, which was greater than the yield loss caused by water limitation. The potential decrease in yield from photo-thermal-water-nutrient-limited production to actual yield （YGo） was over 6.0 Mg ha-1, ranging from 4.9 to 8.3 Mg ha^-1 across the entire study region, and it was more obvious in the southern area than in the northern area. These findings suggest that across the main winter wheat production region, the highest yield gap was induced by thermal resources, followed by other factors, such as the level of farming technology, social policy and economic feasibility. Furthermore, there are opportunities to narrow the yield gaps by making full use of climatic resources and developing a reasonable production plan for winter wheat crops. Thus, meeting the challenges of food security and sustainability in the coming decades is possible but will require considerable changes in water and nutrient management and socio-economic policies.
基金supported by the Natural Science Foundation of Guangdong Province,China (6025378,S2011010000983)
文摘Leaf thickness is an important morphological trait in rice. Its association to the yield potential, as of now has not been documented because of the shortage of the equipment which could conveniently measure the leaf thickness in rice. In this study, the thickness of top three leaves of 208 cultivars had been determined by a nondestructive rice leaf thickness instrument for the research of the natural variation of leaves thickness and its association to yield traits in indica rice. The results showed that the flag leaf was the thickest, and the 2nd leaf was thicker than the 3rd leaf. Analysis of variance indicated the existence of wide genetic diversity of leaf thickness among the investigated indica rice genotypes. The tight correlation among the thicknesses of the top three leaves means that the leaf thickness traits share one genetic control system. Leaf thickness had a significant positive correlation with leaf length and a positive correlation with leaf width, indicated that thicker leaf was beneficial to increasing the single leaf area. The results of correlation analysis revealed that thicker leaf should be profitable to the leaf erection, higher numbers of grains per panicle and higher grains weight per panicle. However, the significantly negative correlation between leaf thickness and number of panicles per plant counteracted the profitability from increased grains weight per panicle, so that the correlations of the thicknesses of the top three leaves to yield and biomass were positive but not significantly. It has made great progress in the genetic improvement of leaves thickness in inbred indica rice breeding in Guangdong Province, China, since the 1990s.
基金supported by the National Key Research and Development Program(2016YFD0100700)the Wuhan Science and Technology Project(2020020601012259)+4 种基金Hubei Natural Science Foundation(2020CFB117)the National Natural Science Foundation of China(31301250)the Talent Project from Guizhou Education Department(Qian jiao he KY zi(2021)024)the Key Cultivation Project of Guizhou University(201903)the Talent Project from Thousands of Innovative and Entrepreneurial in Guizhou Province。
文摘Rice has a large number of nitrate or peptide transporter family(NPF) genes, but the effects of most members on rice growth and development are unknown. We report that Os NPF5.16, a nitrate transporter gene with natural variation in its promoter sequence, is essential for rice growth and yield. The promoter sequence showed various differences between indica and japonica cultivars, and higher expression of Os NPF5.16 was found in indica cultivars with higher plant weight and more tillers than japonica cultivars.Os NPF5.16 was highly expressed in roots, tiller basal parts, and leaf sheaths, and its protein was localized on the plasma membrane. In c RNA-injected Xenopus laevis oocytes, Os NPF5.16 transport of nitrate at high nitrate concentration depended on p H. Overexpression of Os NPF5.16 increased nitrate content and total nitrogen content in leaf sheath as well as biomass and tiller bud length in rice. Elevated expression of Os NPF5.16 increased rice tiller number and grain yield by regulating cytokinin levels. Inhibition of Os NPF5.16 expression showed the opposite effects. Regulating Os NPF5.16 expression has potential for improving rice grain yield.
基金supported by grants from the National Natural Science Foundation of China (31101635, 31471995 and 31770428)Zhejiang Provincial Foundation of Science (LY14C030007)Open Fund of Jiangsu Key Laboratory for Biodiversity and Biotechnology
文摘Detailed information on venom yield is helpful in preparing antivenoms and treating snakebites, but such information is lacking for many species of venomous snakes. The Chinese cobra(Naja atra) is a large sized, venomous snake commonly found in southeastern China, where it causes a heavy burden of snakebites. To examine the effects of various factors(morphology, sex, age, season, and geographical origin) on the venom yield in this snake, we collected venom samples of 446 individuals(426 adults and 20 neonates) from 10 populations of N. atra over an eightyear period. We used two variables, lyophilized venom mass(venom yield) and solid content of venom(% solids), to quantify the venom yield. We used linear regression analysis to check if venom yield was related to morphological factors, one-way ANOVA and one-way ANCOVA to detect the sexual, ontogenetic, and geographic variation in venom yield, and repeated-measures ANOVA to examine seasonal shifts in venom yield. Our results indicate that venom yield of N. atra is positively related to the morphological traits examined, with male snakes expelling more venom than females. Venom yield in N. atra was age-related, with elder snakes always expelling more venom than younger ones. Geographic variation in venom yield was also observed, while seasonal variation was not. The solid content of venom was lower in males than in females, but this was not related to morphology, season, age, or geography. Our findings suggest that venom yield in N. atra is influenced by multiple factors, as well as by the interactions among these factors.
基金supported by the National Basic Research Program of China(2010CB951504,2012CB95590004)the National Natural Science Foundation of China(41171093)the Key Technologies R&D Program of China during the 12th Five-Year Plan period(2012BAC19B01)
文摘Previous studies demonstrated climate change had reduced rice yield in China, but the magnitude of the reduction and the spatial variations of the impact have remained in controversy to date. Based on a gridded daily weather dataset, we found there were obvious changes in temperatures, diurnal temperature range, and radiation during the rice-growing season from 1961 to 2010 in China. These changes resulted in a signiifcant decline of simulated national rice yield （simulated with CERES-Rice）, with a magnitude of 11.5%. However, changes in growing-season radiation and diurnal temperature range, not growing-season temperatures, contributed most to the simulated yield reduction, which conifrmed previous estimates by empirical studies. Yield responses to changes of the climatic variables varied across different rice production areas. In rice production areas with the mean growing-season temperature at 12-14＆#176;C and above 20＆#176;C, a 1＆#176;C growing-season warming decreased rice yield by roughly 4%. This decrease was partly attributed to increased heat stresses and shorter growth period under the warmer climate. In some rice areas of the southern China and the Yangtze River Basin where the rice growing-season temperature was greater than 20＆#176;C, decrease in the growing-season radiation partly interpreted the widespread yield decline of the simulation, suggesting the signiifcant negative contribution of recent global dimming on rice production in China＇s main rice areas. Whereas in the northern rice production areas with relatively low growing-season temperature, decrease of the diurnal temperature range was identiifed as the main climatic contributor for the decline of simulated rice yield, with larger decreasing magnitude under cooler areas.
基金financially supported by the Key Technologies R&D Program of China during the 12th Five-Year Plan period(2012BAD14B07-01 and 2012BAD14B07-02)
文摘Biomass yields and concentrations of crude protein（CP）, ether extract（EE）, neutral detergent fiber（NDF）, acid detergent fiber（ADF）, and crude fiber（CF） were analyzed for five cultivars of summer-sown maize（Zea mays L.） stover grown in field trials at three rates of N fertilization, and sampled immediately after grain harvest.The results revealed differences in yields and concentrations of nutrients according to stalk height and hence harvest portion among the cultivars.N application greatly increased biomass yield and CP, especially in upper stalks and to a lesser extent, EE.Concentrations of NDF and ADF decreased as N rate increased.The results show that stovers from all local popular maize cultivars are suitable as animal fodder and that moderate N application improves feed quality of stover.
基金jointly supported by the National Key Research and Development Program of China (Grant No. 2021YFD1000401)the National Natural Science Foundation of China (Grant No.32070376)+1 种基金the Program of Horticultural Crop Germplasm Resources in Hubei Province (Grant No. 2021DFE016)the Key Technology of Safety Production to Improve Tea Quality and Efficiency in Three Gorges Reservoir Area。
文摘Many attentions have been previously focused to identify the multiple biochemical components related to tea quality and health benefits,however, the natural variation of biochemical components present in tea germplasm has not been adequately evaluated. In this study, the main biochemical components, leaf morphological and yield characteristics were evaluated for four rounds of tea leaves in a panel of 87 elite tea cultivars suitable for black, green, or oolong tea. Significant variations were observed among the tea cultivars, as well as seasonal differences in the levels of the free amino acid(FAA), caffeine(CAF), tea polyphenols(TP), water extract(WE) and TP to FAA ratio(TP/FAA). Results showed that the average levels of FAA showed a seasonal change, with the highest level of 4.0% in the 1st spring tea in the cultivars suitable for green tea and the lowest of 3.2% in summer tea in the cultivars suitable for black tea. The average CAF content was highest 3.2% in the cultivars suitable for oolong tea in the 1st spring and the lowest 2.5% in the cultivars suitable for green tea in summer. Limited seasonal and varietal variations were noticed in the average levels of WE among the three categories of tea. In addition, significant natural variation of the morphological characteristics, bud length varying from 2.5 cm to 8.7 cm, bud density from 190.3 buds · m-2to 1 730.3 buds · m-2, mature leaves biomass from 128.4 kg · hm-2to 2 888.4 kg · hm-2, and yield component traits of 100 buds(one bud with two leaves) dry weight from 3.7 g to37.7 g, tea yield/round from 444.6 kg · hm-2to 905.3 kg · hm-2, were observed. The aim of our evaluation was not only to identify the advantages of seasonal and clonal variations but also to provide a new viewpoint for their further application. Representative accessions were selected from the germplasm to promote the establishment of an inherent biochemical constituent expressing the quality of black, green, and oolong tea. The findings might be utilized to establish early selection criteria to enhance the tea breeding and production program.
基金supported by National Natural Science Foundation of China(No.41172231)
文摘Regime of groundwater level is a comprehensive reflection of the hydrogeological environment from the perspective of groundwater. Based on the analysis of the water-level change of 65 groundwater monitoring points from 1987 to 1990, it is found that intermittent cones of depression came into being due to groundwater exploitation in Guilin during the observation period. The buried depth of groundwater in the drawdown cones, the annual variation of water level and specific yield have higher values. Improvement has been made to the formula of infiltration coefficient of precipitation. By using the precipitation response data recorded at every 15 minutes for water level of No. 9 borehole which is near Zengpiyan Cave, the specific yield of phreatic variation zone is indirectly calculated by using the modified formula. The results are range from 0.012 to 0.462 and the spatial distribution of specific yield is ascertained. These make up the deficiency that empirical values cannot be categorized based on the actual conditions. What’s more, the widely used Aviriyanover’s empirical formula is poorly applicable to karst area. This is due to its strict requirement for outside conditions, such as shallow buried depth, homogeneous aquifer medium and small hydraulic gradient.
基金supported by grants from the National Key Research and Development Program of China(2016 YFD0300108)the National Natural Science Foundation of China(31671630)the earmarked fund for China Agriculture Research System(CARS-01-04A)。
文摘Environmental conditions greatly affect the growth of rice. To investigate the geographic differences in yield formation of single-season high-yielding hybrid rice in southern China, experiments were conducted in 2017 and 2018 in the upper and middle–lower reaches of the Yangtze River with 10–30 main locally planted high-yielding hybrid cultivars used as materials. Compared with rice planted in the middle–lower reaches of the Yangtze River, rice planted in the upper reaches has a longer tillering duration, higher accumulated temperature(≥10℃) during tillering period, but lower accumulated temperature and solar radiation from initial booting to maturity. Yield traits comparison between the upper and the middle–lower reaches of Yangtze River showed that the former had 48.1% more panicles per unit area while the latter had 46.4% more grains per panicle;the rice yield in the former was positively correlated with the seed setting rate and the dry matter accumulation before heading, while the latter was positively correlated with grains per panicle and dry matter accumulation from booting to maturity. Comparison of the same variety Tianyouhuazhan planted in different regions showed there was a significant positive correlation between panicle number and the duration of and accumulated temperature during the tillering period(r=0.982^(**), r=0.993^(**), respectively), and between grains per panicle and accumulated solar radiation during booting period(r=0.952~*). In the upper reaches of the Yangtze River, more than 90% of cultivars with an yield of greater than 11 t ha^(–1) had an effective panicle number of 250–340 m^(–2), and there was a significant negative correlation between seed setting rate and grains per panicle;therefore, the high-yielding rice production in these regions with a long effective tillering period(>40 d) should choose varieties with moderate grains per panicle, adopt crop managements such as good fertilizer and water measures during vegetative growth period to ensure a certain number of effective panicles, and to increase the dry matter accumulation before heading. While in regions with a short effective tillering period(<20 d) but good sunshine conditions during the reproductive growth period, such as the middle–lower reaches of the Yangtze River, high-yielding rice production should choose cultivars with large panicles, adopt good water and fertilizer managements during the reproductive growth period to ensure the formation of large panicles and the increase of dry matter accumulation after heading.
文摘The interactions on rainfed soybean yield among planting date, maturity, and year-to-yearclimate change were studied using CROPGRO-soybean model. Simulations were based on 19 plantingdates, maturity groupsⅢ, ⅣandⅤ, 30 years recorded weather data from Corbin, Suffolk,West Point in Virginia, USA. Yield was similar on early plantings and went down with lateplantings. Both grand and year-to-year variation of soybean yield declined linearly withplanting date. Year-to-year climate variation was dominant yield variation source inrainfed soybean production. Interaction occurred between planting date and maturity.Optimal planting dates for different sites lied within 130th-170th day of a year.Irrigation is recommended for profitable crops, especially in Corbin and West Point.
基金Under the auspices of the National Natural Science Foundation of China (No. 40601027)
文摘Based on the surveys and the statistic data during 1980-2003, the variation character of grain yield per unit area in Northeast China and its main factors have been discussed by the methods of statistics and grey correlation analysis. The results show that: 1) the grain yield per unit area has been taking on an increasing trend in the recent 20 years. It increased from 2519.80kg/ha in 1980 to 4216.11kg/ha in 2003, with an increasing rate of 67.32%; 2) the variation of grain yield per unit area is considerably prominent and its range is also very great, with the maximal increase rate of 42.59% and maximal decrease rate of 21.13%, respectively, which are far above the whole Chinese average level; 3) the variation of main crops' yield per unit area is remarkable, which takes on the character that the yield of corn is much higher than that of soybean and rice; and 4) the grey correlation analysis shows that the most important factors impacting the variation of grain yield per unit area are the total power of agricultural machinery, the consumption of chemical fertilizer and effective irrigated area. However, the influence of natural disaster and income level should not be ignored. Effective ways to improve grain yield per unit area are to construct farmland improvement groundwork, reclaim the middle- and low-yield farmland, etc.
基金the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP,South Korea)(No.2019R1A2C1085272)the R&D Center for Valuable Recycling(Global-Top R&BD Program)of the Ministry of Environment of Korea(No.2016002220003)。
文摘In this work,variation in the dynamic recrystallization(DRX)and dynamic precipitation behavior of AZ80 alloy during extrusion due to changes in extrusion temperature was investigated,and the resultant microstructure and yield asymmetry were analyzed.As the extrusion temperature increases from 250℃to 350℃,the primary DRX mechanism changes from twin-induced DRX to discontinuous DRX,resulting in an increase in the DRX area fraction and un DRXed grain size.In addition,as the extrusion temperature rises,Mg17Al12 precipitation during extrusion decreases sharply throughout the extruded material.The reduction in the compressive yield strength(CYS)with increasing extrusion temperature is more pronounced than it is for the tensile yield strength(TYS),which ultimately increases the yield asymmetry of the extruded material.The higher extrusion temperature has less of an influence on the TYS due to the promotion of certain hardening effects.On the other hand,the greater reduction in the CYS is attributed to the increased fraction and size of regions in which{1012}twins predominantly form and the lower amount of precipitates,which effectively facilitates{1012}twinning.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest, China (No. 201303103)the National Key Research and Development Program, China (No. 2016YFD0200105)the Innovative Group Grant of the National Natural Science Foundation of China (No. 31121062)
文摘Better understanding of the factors that influence crop nitrogen(N) requirement plays an important role in improving regional N recommendations for rice(Oryza sativa L.) production. We collected data from 1 280 plot-level measurements in different reaches of the Yangtze River, China to determine which factors contributed to variability in N requirement in rice. Yield, variety, and cropping system were significantly related to N requirement. The N requirement remained consistent at about 18.6 kg N Mg^(-1)grain as grain yield increased from 7 to 9 Mg ha^(-1), then decreased to 18.1, 16.9, and 15.9 kg N Mg^(-1)grain as yield increased to 9–10, 10–11, and > 11 Mg ha^(-1), respectively. The decreased requirement for N with increasing yield was attributable to declining N concentrations in grain and straw and increased harvest index. Super rice variety had lower N requirement(17.7 kg N Mg^(-1)grain) than ordinary inbred and hybrid varieties(18.5 and 18.3 kg N Mg^(-1)grain, respectively), which was a result of lower grain and straw N concentrations of super rice. The N requirements were 19.2, 17.8, and 17.5 kg N Mg^(-1)grain for early, middle, and late rice cropping systems, respectively. In conclusion, the rice N requirement was affected by multiple factors, including yield, variety, and cropping system, all of which should be considered when planning for optimal N management.
